With the death of his father, God deprived him of all human support and directed him to the realization that there is no deity but God, Who has no partners.
His grandfather and uncle protected him to some extent, but he came to perceive that his real guardian was God. Behind every phenomenon and every cause and effect, he could discern the hand of the Single Creator of the universe and of causes. The Oneness of God would be manifested to him in the light of Divine Unity. That is, he would be tested in this world of wisdom, where material causes and means have a part in every attainment, and so would have to use necessary material causes and means and take all necessary measures to attain anything. He would have to depend wholly on his Lord and ask Him for any help, thereby demonstrating that only God creates the result and gives success.
As a result of his father's death, he came to be called the "Matchless Orphan Pearl." In reference to this, God addressed him years later: Your Lord shall give you, and you shall be satisfied. Did He not find you an orphan and shelter you?... Did He not find you needy and suffice you? As for the orphan, do not oppress him, and as for the beggar, scold him not (93:5-6, 8-10).
The Matchless Orphan Pearl also lost his mother, Amina, at an early age. When she died in Abwa at age 25 or 26 on her way back from visiting her husband's tomb in Madina, Muhammad was only 6 years old. Thus, he learned the pain of having no father or mother. Indeed, he would learn and suffer everything, for he was sent to teach everything to humanity and to be an example in every respect.
His grandfather 'Abd al-Muttalib, a respected Makkan elder, undertook his protection. For this reason, God saved 'Abd al-Muttalib from misfortune. He embraced his beloved grandson, and always offered him the seat of honor in his house. He felt that Muhammad would grow up to save humanity. Muhammad was so noble and well-mannered that his grandfather anticipated his Prophethood. He was not the first of his noble forefathers to do so, however; Ka'b ibn Luayy, who some consider a Prophet, predicted that the Last Messenger would be raised from his own progeny. He mentioned him by name:
Suddenly Prophet Muhammad will appear;
He will give tidings, and is truthful in his tidings.
'Abd al-Muttalib, whom even the great army of Abraha could not bring to tears, wept bitterly when he took to his deathbed. When his son, Abu Talib, asked what was wrong, he replied: "I'm weeping because I'll no longer be able to embrace Muhammad," and then added: "I'm afraid something might happen to my Matchless Pearl. I entrust him to you for safekeeping."
Abu Talib assumed Muhammad's protection and, in return, his son 'Ali would be blessed with being the father of Muhammad's progeny. After Prophethood, the Messenger of God said to 'Ali: "Every other Prophet's progeny descended from himself, but my progeny will descend from you." 'Ali would be the father and the greatest saint until the Last Day, as the representative of the Prophet's sainthood. This is Abu Talib's reward for helping Muhammad.
Abu Talib protected Muhammad with great care. Historians and biographers, such as Ibn Ishaq, relate that Abu Talib took his nephew to Syria in a trade caravan when he was 10 or 12 years old. They stopped somewhere near Damascus and left him, as he was the youngest, to watch over the caravan. From his nearby monastery, the Christian monk Bahira was observing the caravan. This monk was expecting the arrival of the Last Prophet, and so always studied people. He noticed that a cloud followed the caravan, stopping and starting when the caravan did so, in order that one of its members would be shaded.  He thought: "This is a special characteristic of the Prophets. The expected Prophet must be in that caravan."
When the caravan stopped near his monastery, Bahira invited its members over for a meal. Noticing the cloud still hovering over the caravan, he asked Abu Talib if someone had been left behind. Abu Talib answered that they had left a young boy to watch over their things. The monk asked them to fetch him. When Muhammad came, Bahira took Abu Talib to one side and asked him about his relationship with the boy. "He is my son," Abu Talib answered, but Bahira disputed this, saying: "He can't be your son. According to our books, his father must have died before his birth." Then he added: "Let me give you this advice. Take this boy back immediately. The Jews are envious. If they recognize him, they'll harm him." Abu Talib made an excuse to the other caravan members and returned to Makka with his nephew. 
Prophet Muhammad made a second journey when he was 25 years old, with the trade caravan of Khadija, a respected widow he would later marry. On the journey, he encountered Bahira once more. The monk was very pleased with this second meeting, and told him: "You will be a Prophet, the Last Prophet. I wish that God would allow me to live to see you raised as a Prophet. I would follow you, carry your shoes and protect you against your enemies!"
Another major event of Muhammads' early life was the fijar (sacrilegious) war that occurred during his later teens. This was the fourth war that violated the sanctity of the sacred months (Dhu al-Qa'dah, Dhu al-Hijjah, Muharram, and Rajab) and the sacred territory of Makka. Its immediate cause was two men's jealousy and animosity. One belonged to the Banu Kinanah (a confederate of the Quraysh tribe) and the other to the Qays-'Aylan (an important clan of the Hawazin tribe). The future Prophet, who would end all injustice and lawlessness, helped his uncle Zubayr ibn 'Abd al-Muttalib, who represented Banu Hashim in the war, gather the arrows shot by the enemy.
Another important event was his presence at the meeting that resulted in the hilf al-hudul (the alliance of the virtuous). This league against injustice was sponsored mainly by the Banu Hashim and the Banu al-Muttalib tribes. It was formed to ensure that foreign merchants would no longer be deprived of their rights, as happened when the Qurayshi 'As ibn Wa'il usurped a Yemeni merchant's goods. The Yemeni appealed to the Qurayshi leaders for help, but they ignored him. When the Banu Hashim, Muhammad's clan, heard of this, they decided to form the hilf al-fudul and force the return of the merchant's money. They also took an oath that whenever they someone in Makka, whether citizen or stranger, suffered an injustice, they would offer their support until justice was done. Muhammad was so impressed with its noble objectives that he would say long after: "I attended the conclusion of an agreement at 'Abd Allah ibn Jud'an's house. I would not exchange it for the best material gain. If someone appeals to it in Islam, I would respond."
Muhammad's childhood and youth were a prelude to his Prophethood. Besides his other exalted and laudable characteristics, everyone agreed upon his truthfulness and trustworthiness. He never lied, cheated, broke his word, or participated in pagan rituals (jahiliyya). He was called "the Truthful, Trustworthy Man" even by his bitterest enemies.
People would say of him: "If you have to travel and need someone to look after your wife, entrust her to Muhammad without hesitation, for he will not even glance at her face. If you want to entrust your wealth for safeguarding, entrust it to this trustworthy, honest man, for he will never touch it. If you look for someone who never tells a lie and never breaks his word, go directly to Muhammad, because whatever he says is true."
Those who knew him from his childhood immediately believed in him when he declared his Prophethood. Among them were Abu Bakr, 'Uthman, Talha, Zubayr, Abu Dharr, and Yasir. When 'Ammar told Yasir (his father) that he believed in Muhammad the latter responded: "If Muhammad says that God is One, it is true. He never lies."
In the early days of his Prophethood, Prophet Muhammad once summoned the Qurayshis to the foot of Abu Qubays hill. He asked them: "Would you believe me if I told you an enemy host was waiting behind this hill to attack you?" Everyone answered that they would, even his uncle Abu Lahab, who would become his bitterest enemy. 
When humanity was in dire need of someone to destroy unbelief and breathe new life into the world, God raised Muhammad to stop all forms of wickedness. In the words of Ahmad Shawky:
The sun of guidance was born, and the entire universe was illumined.
A smile appeared on the lips of time, and his praises were sung.
When he appeared on the horizon of Madina years later, the pure, innocent children of that illumined city would sing his praises as follows:
The "full moon" rose upon us from the hills of Wada',
So it is incumbent upon us to thank God so long as
Those who pray and entreat Him continue to do so. 
 Ibn Hisham, Sira, 1:191.
 Sahih al-Bukhari, Tafsir, 1:111; Sahih al-Muslim, Iman, 355.
 Ibn Kathir, al-Bidaya, 3:241.